A 34-year-old primigravida at 18 weeks gestation comes to the office for a routine prenatal examination.  The patient’s pregnancy has been uncomplicated.  She takes a prenatal vitamin daily, and her laboratory results have been normal to date.  The patient’s personal and family medical histories are unremarkable.  During the visit, a detailed fetal ultrasound examination reveals severe unilateral hydronephrosis; there is no ureteral dilation.  Male external genitalia are also visible.  If the fetal hydronephrosis is caused by obstruction, which of the following is the most likely site?

A 2-week-old boy is brought to the clinic by his parents for evaluation of his umbilicus.  The parents report that since the umbilical cord stump separated 2 days ago, there has been drainage from the umbilicus that increases when the patient cries.  He is exclusively breastfed and continues to have normal wet diapers and stool output.  The patient was born at term, and the pregnancy and delivery were uncomplicated.  Vital signs are normal.  Physical examination of the abdomen shows clear to pale yellow fluid leaking from the umbilical stump site with mucosal tissue at the base of the umbilicus.  Samples are obtained for complete blood count.  Laboratory results are as follows:

Which of the following is the most likely cause of this patient’s umbilical findings?

A 32-year-old woman comes to the office at 28 weeks gestation due to dyspnea.  She has been feeling short of breath when she is supine but has no other symptoms. The patient has had no prenatal care during her pregnancy.  She has a history of epilepsy that is well-controlled with medication.  She lives with her husband and does not use tobacco, alcohol, or illicit drugs.  Her immunizations are up to date, and she has no allergies.  Physical examination shows a uterine size that is larger than expected for gestational age.  Sonographic assessment shows markedly elevated amniotic fluid levels.  Which of the following fetal anomalies would most likely account for this patient’s polyhydramnios?

A 1-hour-old boy is in the neonatal intensive care unit due to tachypnea and hypoxia.  The infant was born at 39 weeks gestation via cesarean delivery due to recurrent variable decelerations.  The pregnancy was complicated by lack of prenatal care.  The infant weighs 3.2 kg (7 lb 1 oz).  Physical examination shows a flattened nose and bilateral club feet.  Breath sounds are markedly diminished bilaterally.  The infant is intubated and mechanically ventilated, but oxygen levels do not improve.  He dies an hour later.  Which of the following is most likely to be found during autopsy of this infant?

A 40-year-old nulligravida woman comes to the office with a 2-month history of worsening right pelvic pain.  She experiences the pain daily, and its intensity does not vary during her menstrual cycle.  In addition, the patient’s waist size has increased despite a decreased appetite.  Pelvic examination shows an irregularly shaped, fixed adnexal mass.  One week later, she undergoes surgery to remove a large ovarian neoplasm.  Within the true pelvis, the surgeon can most likely palpate the right ureter immediately anterior to which of the following structures?

A 21-year-old man comes to the emergency department after suffering an injury during a football game.  He was falling to the ground when he was struck forcefully from behind by the helmet of an opposing player.  The patient was able to ambulate after the injury but has since had severe pain worsened by deep breaths.  His blood pressure is 110/65 mm Hg, pulse is 110/min, and respirations are 16/min.  On examination, there is bruising and tenderness over the left posterior chest wall.  There is normal spinal range of motion and no midline tenderness.  Gait and lower extremity neurologic examination are normal.  Imaging studies reveal a fracture of the left 12th rib.  Which of the following structures is most likely to be lacerated by the fractured bone?

A 47-year-old woman comes to the office due to fever, dysuria, and abdominal pain.  The patient has had several urinary tract infections since her teens but has no other medical concerns.  Physical examination shows mild suprapubic discomfort.  Urinalysis demonstrates pyuria and many bacteria.  CT scan of the abdomen is shown in the image below:

Which of the following structures has most likely limited the proper ascent of the anomalous organ seen on CT scan?

A 65-year-old man comes to the emergency department due to severe lower abdominal pain and nausea.  He also has not been able to urinate for the past 24 hours.  The patient has a history of hypertension and benign prostatic hyperplasia.  On examination, a large mass is palpable in the suprapubic area.  Multiple attempts at urethral catheterization are unsuccessful, and an ultrasound-guided midline suprapubic cystostomy is planned.  Besides the bladder wall, which of the following structures is most likely to be penetrated by the trocar and cannula during the procedure?

A 45-year-old man with a history of end-stage renal disease undergoes renal allograft transplantation.  The donor kidney and proximal ureter are transplanted in the right iliac fossa, with implantation of the ureter into the patient’s bladder.  Six days following surgery, the donor kidney appears to be functioning well, but the patient develops fever and right lower quadrant abdominal pain.  Imaging studies reveal a large pelvic fluid collection.  Exploratory laparotomy is performed and discovers urinary leakage, with significant ischemia and necrosis of the transplanted ureter immediately adjacent to the site of implantation into the bladder.  The proximal portion of the ureter appears normal.  The healthy segment of this patient’s transplanted ureter is most likely receiving blood from which of the following arteries?

A 39-year-old woman is admitted to the hospital for a total abdominal hysterectomy for symptomatic uterine fibroids.  The largest fibroid, measuring 8 cm, is located in the lower aspect of the uterus at the level of the cardinal ligament, compressing the bladder anteriorly.  The patient has no other medical conditions and no prior surgeries.  After the surgery, she develops right-sided back pain.  The patient has been able to urinate without difficulty.  Injury to which of the following structures is the most likely explanation for this patient’s postoperative symptoms?

A 30-year-old woman comes to the clinic due to recurrent urinary tract infections.  She also has a history of nephrolithiasis.  Vital signs are normal, and examination is unremarkable.  CT scan of the abdomen is shown below.

Fusion of which of the following embryologic structures most likely explains this patient’s CT scan findings?