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ABPath Pediatric Pathology study materials
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ABPath Pediatric Pathology practice questions

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Question 1Embryologic, fetal and childhood growth and development

At approximately what gestational age does the human embryonic heart begin to beat?

  1. Day 60 after fertilization
  2. Day 8 after fertilization
  3. Day 22 after fertilization Correct answer.
  4. Day 45 after fertilization

Explanation

Cardiac contractions begin around the fourth week (about day 22 post-fertilization), shortly after the primitive heart tube forms and begins looping. Earlier stages show only a linear tube without coordinated contraction.

Question 2Embryologic, fetal and childhood growth and development

The neural tube in the human embryo normally completes anterior neuropore closure at approximately which day post-fertilization?

  1. Day 56
  2. Day 40
  3. Day 25 Correct answer.
  4. Day 12

Explanation

The anterior neuropore closes around day 25 and the posterior neuropore around day 27-28 post-fertilization. Failure of anterior closure produces anencephaly, and failure of posterior closure produces spina bifida.

Question 3Embryologic, fetal and childhood growth and development

Which structure gives rise to the definitive gut tube and is derived from the hypoblast during gastrulation?

  1. The yolk sac endoderm Correct answer.
  2. The amnion
  3. The chorion
  4. The allantois

Explanation

Endoderm of the secondary yolk sac is incorporated into the embryo during folding to form the primitive gut tube. The amnion and chorion are extraembryonic membranes of ectodermal/trophoblastic origin, and the allantois is a diverticulum of the hindgut.

Question 4Embryologic, fetal and childhood growth and development

A newborn has a midline abdominal wall defect with herniated bowel covered by a translucent membrane, and the umbilical cord inserts at the apex of the membrane. Which structure failed to return to the abdominal cavity?

  1. The hindgut
  2. The midgut Correct answer.
  3. The liver
  4. The stomach

Explanation

Physiologic midgut herniation occurs because the abdominal cavity is temporarily too small; failure of return by about 10-11 weeks produces omphalocele. The membrane covering the herniated viscera is amnion and peritoneum.

Question 5Embryologic, fetal and childhood growth and development

Which of the following best describes the normal timing of the embryonic period in human development?

  1. Weeks 3 through 8 after fertilization Correct answer.
  2. Weeks 1 through 2 after fertilization
  3. Weeks 9 through 20 after fertilization
  4. Weeks 21 through 38 after fertilization

Explanation

The embryonic period spans weeks 3 through 8 post-fertilization, during which organ primordia form and the major body plan is established. After week 8 the conceptus is termed a fetus and growth predominates.

Question 6Embryologic, fetal and childhood growth and development

A fetus is found to have a single umbilical artery. Which additional finding most strongly warrants evaluation for a coexisting structural anomaly?

  1. Male fetal sex
  2. Maternal age over 35 years
  3. Breech presentation
  4. Presence of other sonographic anomalies Correct answer.

Explanation

A single umbilical artery is associated with renal, cardiac, and other structural anomalies, and the risk is substantially higher when other anomalies are already detected. Isolated single umbilical artery carries a lower but still increased risk.

Question 7Embryologic, fetal and childhood growth and development

A 2-day-old term infant has bilious vomiting and a 'double bubble' sign on radiography with no distal gas. Which developmental process most directly explains this finding?

  1. Failure of midgut rotation
  2. Failure of duodenal recanalization Correct answer.
  3. Failure of cloacal septation
  4. Failure of neural crest migration

Explanation

Duodenal atresia results from failure of the duodenal lumen to recanalize during the solid-cord stage of gut development. The double bubble with absent distal gas reflects complete obstruction proximal to the ligament of Treitz.

Question 8Embryologic, fetal and childhood growth and development

A term neonate has respiratory distress, and chest radiography shows bowel loops in the left hemithorax with mediastinal shift. Which embryologic structure failed to close?

  1. The pleuroperitoneal membrane Correct answer.
  2. The pleuropericardial fold
  3. The dorsal mesentery
  4. The septum transversum

Explanation

Congenital diaphragmatic hernia results from failure of the pleuroperitoneal membranes to close the pericardioperitoneal canals by about week 8, allowing abdominal viscera into the thorax. Left-sided defects are most common.

Question 9Embryologic, fetal and childhood growth and development

Which of the following best explains why the fetal circulation preferentially directs oxygenated blood from the umbilical vein to the left atrium?

  1. The foramen ovale directs blood from the right to the left atrium Correct answer.
  2. The ductus arteriosus carries blood from the pulmonary artery to the aorta
  3. The umbilical arteries carry oxygenated blood to the placenta
  4. The ductus venosus shunts blood directly to the inferior vena cava

Explanation

Highly oxygenated blood from the umbilical vein reaches the right atrium and is preferentially streamed through the foramen ovale into the left atrium. This ensures oxygen-rich blood supplies the developing brain and heart.

Question 10Embryologic, fetal and childhood growth and development

A newborn has a small mandible, glossoptosis, and a U-shaped cleft palate. Which developmental process underlies the micrognathia?

  1. Failure of the lateral palatine shelves to elevate
  2. Hypoplasia of the first pharyngeal arch Correct answer.
  3. Defective fusion of the medial nasal prominences
  4. Abnormal regression of the second pharyngeal arch

Explanation

The mandible derives largely from the first pharyngeal arch; hypoplasia produces micrognathia, which allows the tongue to displace posteriorly and prevents palatal shelf fusion. This triad is Pierre Robin sequence.

Question 11Embryologic, fetal and childhood growth and development

A fetus has severe oligohydramnios from bilateral renal agenesis. Which consequence is most directly attributable to the reduced amniotic fluid?

  1. Ductus arteriosus constriction
  2. Polyhydramnios-induced uterine overdistension
  3. Pulmonary hypoplasia Correct answer.
  4. Neural tube defects

Explanation

Fetal urine is the main source of amniotic fluid in later gestation; its absence causes oligohydramnios and impaired lung growth, producing pulmonary hypoplasia. This is part of the Potter sequence.

Question 12Embryologic, fetal and childhood growth and development

Which of the following findings at birth is most characteristic of a defect in the development of the urorectal septum?

  1. An imperforate anus with a rectovaginal fistula Correct answer.
  2. A horseshoe kidney
  3. A single umbilical artery
  4. A patent urachus

Explanation

The urorectal septum divides the cloaca into urogenital and anorectal portions; defective septation produces anorectal malformations such as imperforate anus with fistulae. Horseshoe kidney and patent urachus arise from different developmental errors.

Question 13Embryologic, fetal and childhood growth and development

A 3-week-old infant presents with projectile nonbilious vomiting and a palpable olive-shaped mass. Which embryologic change most directly underlies this condition?

  1. Malrotation of the midgut
  2. Failure of the pyloric lumen to recanalize
  3. Hypertrophy of the pyloric circular muscle Correct answer.
  4. Failure of the duodenal C-loop to rotate

Explanation

Hypertrophic pyloric stenosis reflects acquired hypertrophy of the pyloric circular muscle, producing nonbilious projectile vomiting in early infancy. It is not a failure of recanalization, which would cause atresia.

Question 14Embryologic, fetal and childhood growth and development

A fetus has a large sacrococcygeal mass composed of all three germ layers. Which developmental process most plausibly accounts for this lesion?

  1. Remnants of the primitive streak Correct answer.
  2. Failure of neural crest migration
  3. Persistence of the notochord
  4. Abnormal closure of the anterior neuropore

Explanation

Sacrococcygeal teratomas arise from remnants of the primitive streak, which is pluripotent and can form all three germ layers. They are the most common congenital tumor of the newborn.

Question 15Embryologic, fetal and childhood growth and development

A male infant has ambiguous genitalia, and evaluation reveals a 46,XY karyotype with normal testosterone synthesis but absent androgen receptor function. Which developmental principle best explains the phenotype?

  1. Mullerian structures regress only when AMH is absent
  2. Wolffian structures develop in the absence of testosterone
  3. Gonadal sex is determined by the number of X chromosomes
  4. External genital virilization requires androgen receptor signaling Correct answer.

Explanation

Male external genital virilization depends on androgen receptor-mediated signaling; without it, the genitalia remain undervirilized or female-appearing despite testosterone production. Wolffian structures also require androgen signaling for maintenance.

Question 16Embryologic, fetal and childhood growth and development

A neonate has a large omphalocele and macroglossia, and the pregnancy was complicated by polyhydramnios. Which condition best fits this presentation?

  1. Potter sequence
  2. Trisomy 18
  3. Beckwith-Wiedemann syndrome Correct answer.
  4. Down syndrome

Explanation

Beckwith-Wiedemann syndrome features omphalocele, macroglossia, and visceromegaly, often with polyhydramnios and neonatal hypoglycemia. It results from abnormal imprinting of growth-regulatory genes on chromosome 11p15.

Question 17Embryologic, fetal and childhood growth and development

A fetus has severe early growth restriction with a karyotype showing triploidy. Which mechanism best explains the placental findings often seen with this karyotype?

  1. A single gene mutation in a growth factor receptor
  2. Maternal uniparental disomy of chromosome 11
  3. Loss of the paternal X chromosome
  4. An abnormal ratio of paternal to maternal genomic contributions Correct answer.

Explanation

Triploidy creates an abnormal balance of paternally and maternally imprinted genes, contributing to severe growth restriction and placental abnormalities such as a partially molar placenta. Imprinted gene dosage is central to fetal and placental growth.

Question 18Maternal-fetal interactions

Maternal smoking during pregnancy most strongly increases the risk of which placental finding?

  1. Placental infarcts Correct answer.
  2. Chorioamnionitis
  3. Villous edema
  4. Decidual necrosis

Explanation

Tobacco exposure causes vascular injury with reduced uteroplacental perfusion, producing ischemic change including placental infarction. Villous edema and inflammation are linked to other processes such as hydrops and infection.

Question 19Maternal-fetal interactions

A neonate born to a mother with poorly controlled pregestational diabetes is most likely to show which finding at birth?

  1. Severe intrauterine growth restriction
  2. Generalized edema with anemia
  3. Macrosomia with organomegaly Correct answer.
  4. Microcephaly with cataracts

Explanation

Maternal hyperglycemia drives fetal hyperinsulinemia, producing overgrowth with increased fat and organ size. Growth restriction, cataracts, and hydrops are not the typical pattern of diabetic pregnancy.

Question 20Maternal-fetal interactions

Which maternal infection is associated with fetal hydrops due to parvovirus-like suppression of erythropoiesis?

  1. Herpes simplex virus
  2. Cytomegalovirus
  3. Listeria monocytogenes
  4. Parvovirus B19 Correct answer.

Explanation

Parvovirus B19 infects erythroid precursors and causes severe fetal anemia, leading to hydrops. The other listed organisms cause different patterns of fetal injury.

Question 21Maternal-fetal interactions

Rh alloimmunization causes fetal anemia primarily through which mechanism?

  1. Complement-mediated hemolysis of fetal red cells Correct answer.
  2. Maternal T-cell infiltration of villi
  3. Direct marrow infection
  4. Placental transfer of maternal iron

Explanation

Maternal anti-D crosses the placenta and binds fetal Rh-positive red cells, leading to immune hemolysis and anemia. Infection, cellular infiltration, and iron handling are not the operative mechanism.

Question 22Maternal-fetal interactions

Maternal use of which drug during pregnancy is most associated with fetal renal dysgenesis and oligohydramnios?

  1. Penicillin
  2. Insulin
  3. Angiotensin-converting enzyme inhibitors Correct answer.
  4. Acetaminophen

Explanation

ACE inhibitors block fetal angiotensin II, impairing renal development and causing oligohydramnios. The other agents are not recognized teratogens of this type.

Question 23Maternal-fetal interactions

A placenta from a pregnancy complicated by severe preeclampsia shows increased syncytial knots, villous agglutination, and distal villous hypoplasia. These findings indicate which process?

  1. Chronic histiocytic intervillositis
  2. Massive perivillous fibrin deposition
  3. Villitis of unknown etiology
  4. Maternal vascular underperfusion Correct answer.

Explanation

These villous changes reflect reduced maternal spiral artery flow and ischemia. Villitis, fibrin deposition, and intervillositis have distinct inflammatory or depositional patterns.

Question 24Maternal-fetal interactions

Which placental lesion is most characteristic of maternal floor infarction?

  1. Villous edema with trophoblastic hyperplasia
  2. Fetal thrombus in stem villi
  3. Neutrophilic infiltration of the amnion
  4. Diffuse perivillous fibrinoid deposition with trophoblast entrapment Correct answer.

Explanation

Maternal floor infarction is a misnomer for extensive perivillous fibrinoid material trapping villi, associated with poor perinatal outcomes. The other options describe infection, molar change, and fetal vascular lesions.

Question 25Maternal-fetal interactions

A 32-week stillborn fetus has a growth-restricted placenta with multiple infarcts and decidual vasculopathy. Which maternal condition best explains this pattern?

  1. Chronic hypertension Correct answer.
  2. Maternal hypothyroidism treated with levothyroxine
  3. Gestational diabetes with euglycemia
  4. Well-controlled asthma

Explanation

Chronic hypertension produces hypertensive decidual vasculopathy and placental infarction with fetal growth restriction. The other conditions are not typically associated with this vascular pattern.

Question 26Maternal-fetal interactions

A neonate has a small flat hemangioma, thrombocytopenia, and a history of maternal chorionic villus sampling. This presentation suggests which diagnosis?

  1. Kasabach-Merritt phenomenon
  2. Fetomaternal hemorrhage Correct answer.
  3. Neonatal alloimmune thrombocytopenia
  4. Twin-twin transfusion syndrome

Explanation

Instrumentation such as CVS can cause fetomaternal hemorrhage, producing anemia and thrombocytopenia with a small cutaneous lesion. Kasabach-Merritt involves a large vascular tumor, and twin-twin transfusion requires monochorionic twins.

Question 27Maternal-fetal interactions

Which finding in a monochorionic twin pregnancy indicates the donor twin in twin-twin transfusion syndrome?

  1. Enlarged bladder with normal amniotic fluid
  2. Plethoric skin with polycythemia
  3. Oligohydramnios with growth restriction Correct answer.
  4. Polyhydramnios with cardiac hypertrophy

Explanation

The donor twin loses blood to the recipient, becoming oliguric with oligohydramnios and growth restriction. The recipient develops polyhydramnios, plethora, and cardiac strain.

Question 28Maternal-fetal interactions

Maternal hyperthyroidism with thyroid-stimulating immunoglobulins can produce which fetal effect?

  1. Fetal pancreatic hyperplasia
  2. Fetal goiter with hypothyroidism
  3. Fetal bradycardia with macrocephaly
  4. Fetal tachycardia and growth restriction Correct answer.

Explanation

TSI crosses the placenta and stimulates the fetal thyroid, causing tachycardia and growth restriction. Goiter with hypothyroidism results from antithyroid drugs or iodine excess, not TSI.

Question 29Maternal-fetal interactions

A newborn of a mother with systemic lupus erythematosus has complete congenital heart block. Which maternal antibody is most implicated?

  1. Anti-histone
  2. Anti-dsDNA
  3. Anti-Ro/SSA Correct answer.
  4. Anti-cardiolipin

Explanation

Anti-Ro/SSA antibodies cross the placenta and injure the fetal conduction system, causing heart block. The other antibodies are associated with lupus activity or thrombosis but not congenital heart block.

Question 30Maternal-fetal interactions

Which feature distinguishes congenital Zika syndrome from congenital cytomegalovirus infection?

  1. Chorioretinitis with hearing loss
  2. Severe cortical thinning with arthrogryposis Correct answer.
  3. Hepatosplenomegaly with jaundice
  4. Periventricular calcifications

Explanation

Zika produces severe cortical thinning, microcephaly, and arthrogryposis from fetal brain disruption. CMV more often shows periventricular calcifications, hepatosplenomegaly, and sensory deficits.

Question 31Maternal-fetal interactions

A pregnancy with maternal obesity and gestational diabetes shows a placenta with villous immaturity and increased syncytial knots. Which mechanism best explains these changes?

  1. Maternal floor infarction
  2. Chronic villitis from ascending infection
  3. Altered maternal metabolic milieu affecting villous maturation Correct answer.
  4. Fetal thrombotic vasculopathy

Explanation

Maternal metabolic disease alters the placental nutrient and hormonal environment, delaying villous maturation and increasing syncytial knots. Infection, thrombosis, and perivillous fibrin deposition have different histologic signatures.

Question 32Maternal-fetal interactions

A placenta shows massive perivillous fibrin deposition and chronic histiocytic intervillositis. Which maternal association is most likely?

  1. Isolated advanced maternal age
  2. Acute pyelonephritis
  3. Gestational hypertension without proteinuria
  4. Recurrent pregnancy loss with autoimmune features Correct answer.

Explanation

Chronic histiocytic intervillositis and massive perivillous fibrin deposition are linked to maternal autoimmune states and recurrent pregnancy loss. Acute infection or isolated hypertension does not produce this combination.

Question 33Maternal-fetal interactions

Maternal phenylketonuria with poor dietary control most threatens the fetus through which mechanism?

  1. Fetal deficiency of phenylalanine hydroxylase
  2. Maternal hypoglycemia
  3. Maternal hyperphenylalaninemia crossing the placenta Correct answer.
  4. Placental transfer of phenylalanine metabolites causing infarction

Explanation

Elevated maternal phenylalanine crosses the placenta and is teratogenic, causing microcephaly and cardiac defects. The fetal enzyme deficiency and placental infarction are not the operative mechanisms.

Question 34Maternal-fetal interactions

Which maternal nutritional deficiency is most strongly associated with fetal neural tube defects?

  1. Folate deficiency Correct answer.
  2. Iron deficiency
  3. Vitamin B12 deficiency
  4. Vitamin D deficiency

Explanation

Periconceptional folate deficiency is the best-established nutritional risk factor for neural tube defects, and supplementation reduces risk. The other deficiencies cause different fetal problems.

Question 35Abnormalities of the placenta and amniotic fluid

Which placental finding is most characteristic of a complete hydatidiform mole?

  1. Diffuse hydropic villous swelling with trophoblastic proliferation and absent fetal parts Correct answer.
  2. Chorionic villi with marked perivillous fibrin deposition and infarcts
  3. Single umbilical artery with velamentous cord insertion
  4. Focal villous edema with normal villous vasculature and a live fetus

Explanation

A complete mole arises from an androgenetic conception and shows generalized villous hydropic change with circumferential trophoblast proliferation and no fetal tissue. Partial moles show only focal edema, scalloped villi, and often fetal parts.

Question 36Abnormalities of the placenta and amniotic fluid

A placenta shows a velamentous cord insertion with vessels running unsupported through the membranes over the cervical os. Which complication is most directly attributable to this configuration?

  1. Oligohydramnios from renal agenesis
  2. Fetal exsanguination after membrane rupture Correct answer.
  3. Maternal preeclampsia
  4. Placental abruption

Explanation

Vasa previa places unsupported fetal vessels across the cervix, so rupture of membranes can tear them and cause rapid fetal hemorrhage. The risk is fetal, not maternal hypertensive disease.

Question 37Abnormalities of the placenta and amniotic fluid

Which finding best distinguishes a partial hydatidiform mole from a complete mole on histologic examination?

  1. Absent villous vascularization throughout the specimen
  2. Complete absence of any fetal tissue
  3. Focally enlarged villi with scalloped outlines and some fetal red cells in villous vessels Correct answer.
  4. Diffuse circumferential trophoblastic hyperplasia around every villus

Explanation

Partial moles are triploid and retain some fetal tissue and villous capillaries, producing focal edema with scalloped villi and fetal red cells. Complete moles lack fetal tissue and show diffuse, circumferential trophoblast proliferation.

Question 38Abnormalities of the placenta and amniotic fluid

A term placenta has a maternal surface with a central depression and a ring of thickened tissue around the periphery. What is the most likely diagnosis?

  1. Battledore insertion
  2. Succenturiate lobe
  3. Placenta membranacea
  4. Placenta circumvallate Correct answer.

Explanation

Circumvallate placenta has a raised, thickened ring of membranes at the placental margin with a central depression of the chorionic plate. Circummarginate placenta shows a flat transition without the raised ring.

Question 39Abnormalities of the placenta and amniotic fluid

A pregnant patient has a fundal placenta with the cord inserting into the membranes and vessels crossing the internal os. Which prenatal management is most appropriate?

  1. Planned cesarean delivery before labor onset Correct answer.
  2. Induction of labor at 39 weeks
  3. Amniotomy to assess fluid color
  4. Expectant management with serial cervical exams

Explanation

Vasa previa carries a high risk of fetal exsanguination with membrane rupture, so planned cesarean before labor is standard. Digital exams and amniotomy are avoided because they can disrupt the vessels.

Question 40Abnormalities of the placenta and amniotic fluid

Which amniotic fluid finding is most consistent with prolonged membrane rupture and intra-amniotic infection?

  1. Numerous nucleated red blood cells in Wharton jelly
  2. Diffuse perivillous fibrin deposition
  3. Increased syncytial knots with villous agglutination
  4. Neutrophilic infiltrate extending along the chorionic plate and umbilical cord Correct answer.

Explanation

Ascending infection produces a maternal and fetal neutrophil response, seen as chorioamnionitis and funisitis. Perivillous fibrin and syncytial knots reflect maternal underperfusion instead.

Question 41Abnormalities of the placenta and amniotic fluid

A placenta shows a small, firm, pale infarct with villous crowding and loss of intervillous space. Which maternal condition is most strongly associated with such lesions?

  1. Preeclampsia Correct answer.
  2. Gestational diabetes with macrosomia
  3. Maternal opioid use
  4. Acute chorioamnionitis

Explanation

Villous infarction results from obstruction of maternal spiral artery flow and is a lesion of maternal vascular malperfusion, classically associated with preeclampsia. Diabetes tends to produce villous immaturity and hypervascularity rather than infarction.

Question 42Abnormalities of the placenta and amniotic fluid

A placenta from a pregnancy with severe early-onset growth restriction shows distal villous hypoplasia with thin, elongated villi and reduced branching. Which process does this reflect?

  1. Excess trophoblast proliferation from an androgenetic conception
  2. Immune-mediated villous destruction by maternal antibodies
  3. Fetal thrombotic occlusion of umbilical vessels
  4. Impaired maternal spiral artery remodeling with reduced uteroplacental perfusion Correct answer.

Explanation

Distal villous hypoplasia reflects failure of normal spiral artery remodeling, reducing maternal blood flow and impairing villous branching. It is a maternal vascular malperfusion pattern rather than a molar or immune process.

Question 43Abnormalities of the placenta and amniotic fluid

Which finding in the umbilical cord is most suggestive of a long-standing fetal vascular occlusion?

  1. Segmental loss of vessels with fibrin and karyorrhectic debris in the cord stroma Correct answer.
  2. Marginal cord insertion
  3. True knot with intact endothelium
  4. Single umbilical artery

Explanation

Fetal vascular malperfusion can produce stem vessel thrombosis with segmental loss of vessels and necrotic debris in the cord. A single artery and marginal insertion are developmental variants, not occlusive lesions.

Question 44Abnormalities of the placenta and amniotic fluid

Which statement about amniotic fluid volume is correct?

  1. Amniotic fluid is produced mainly by the fetal kidneys in the first trimester
  2. Polyhydramnios is defined by a deepest vertical pocket under 2 cm
  3. Oligohydramnios in the second trimester is associated with pulmonary hypoplasia Correct answer.
  4. Oligohydramnios most often results from fetal swallowing failure

Explanation

Adequate amniotic fluid is needed for fetal lung development, so severe early oligohydramnios can cause pulmonary hypoplasia. Fluid derives largely from fetal urine after early gestation, and swallowing disorders cause polyhydramnios.

Question 45Abnormalities of the placenta and amniotic fluid

A placenta shows a fetus papyraceus with a flattened, compressed sac alongside a normal twin placenta. What is the most likely explanation?

  1. Twin-to-twin transfusion in a monochorionic pair
  2. Maternal floor infarction
  3. Velamentous cord insertion of the surviving twin
  4. Fetal demise in a dichorionic twin gestation Correct answer.

Explanation

Fetus papyraceus is a mummified, compressed fetus resulting from death of one twin, classically in a dichorionic gestation. Monochorionic twin death more often produces vascular anastomotic complications in the survivor.

Question 46Abnormalities of the placenta and amniotic fluid

Which placental finding is most characteristic of a monochorionic twin placenta?

  1. Two separate chorionic discs with fused membranes
  2. Diamniotic membranes with two distinct chorions
  3. Separate placentas with no vascular anastomoses
  4. A single chorionic plate with a thin dividing membrane lacking chorion Correct answer.

Explanation

Monochorionic twins share one chorion with a thin dividing membrane composed of amnion only. Vascular anastomoses are common and underlie twin-twin transfusion complications.

Question 47Abnormalities of the placenta and amniotic fluid

A placenta has a large, well-circumscribed nodule of immature intermediate villi with myxoid stroma and no trophoblastic proliferation. Which diagnosis is most likely?

  1. Placental site trophoblastic tumor
  2. Complete hydatidiform mole
  3. Placental mesenchymal dysplasia Correct answer.
  4. Chorioangioma

Explanation

Placental mesenchymal dysplasia shows enlarged, myxoid stem villi with abnormal vessels but no trophoblastic proliferation, and it can mimic a mole. Trophoblastic proliferation would suggest molar disease instead.

Question 48Abnormalities of the placenta and amniotic fluid

Which form of abortion shows a chorionic sac with an embryo that has died but no hydropic change?

  1. Partial hydatidiform mole
  2. Invasive mole
  3. Missed abortion with a blighted ovum or embryonic demise Correct answer.
  4. Complete hydatidiform mole

Explanation

A missed abortion retains a nonviable gestation without the hydropic villous change and trophoblast proliferation of molar disease. Molar gestations show characteristic villous swelling and proliferation.

Question 49Abnormalities of the placenta and amniotic fluid

A placenta shows a marginal maternal surface with a flat, thin membrane insertion but no raised ring. What is the correct term?

  1. Placenta accreta
  2. Circumvallate placenta
  3. Circummarginate placenta Correct answer.
  4. Placenta increta

Explanation

Circummarginate placenta has a flat transition of membranes at the margin, whereas circumvallate placenta has a raised, thickened ring. Accreta and increta describe abnormal adherence or invasion into the myometrium.

Question 50Abnormalities of the placenta and amniotic fluid

Which condition is most strongly associated with a single umbilical artery in a term infant?

  1. Placental site trophoblastic tumor
  2. Complete hydatidiform mole
  3. Circumvallate placenta
  4. Congenital renal and cardiac anomalies Correct answer.

Explanation

A single umbilical artery is associated with an increased risk of congenital anomalies, particularly renal and cardiac defects. It is a developmental cord anomaly, not a trophoblastic or shape disorder.