A 33-year-old woman, gravida 2 para 1, at 29 weeks gestation comes to the emergency department due to right-sided abdominal pain. The pain developed yesterday morning, initially resolved with acetaminophen, but has become increasingly severe over the past few hours. The patient now has continuous nausea and has vomited twice. She has not had a bowel movement in 2 days. She has had uterine contractions, but no vaginal bleeding or leakage of fluid. The patient has no chronic medical conditions, and her only surgery was a cesarean delivery for failure to progress. Temperature is 37.2 C (99 F), blood pressure is 130/80 mm Hg, and pulse is 118/min. BMI is 30 kg/m². Fetal heart rate monitoring shows a baseline of 160/min and no decelerations. Tocodynamometry shows regular uterine contractions every 1-2 minutes. The abdomen is tender to palpation, but has no rebound or guarding. The uterus has fundal tenderness and an associated firm, tender mass. On pelvic examination, the cervix is closed. Leukocyte count is 19,000/mm³. Urinalysis is normal. Which of the following is the most likely diagnosis in this patient?

Question

Quizplus · Accepted Answer

This patient at 29 weeks gestation has acute-onset, right-sided abdominal pain. Abdominal pain in pregnancy can have a variety of etiologies from both benign and life-threatening causes. This patient with fundal tenderness and a firm, tender mass most likely has a degenerating uterine leiomyoma. Leiomyomata uteri (fibroids) are benign myometrial tumors that can grow rapidly during pregnancy due to elevated estrogen and progesterone levels. However, because myometrial blood flow shifts toward the developing fetus and placenta during pregnancy, fibroids can outgrow their blood supply, leading to fibroid infarction and necrosis. Therefore, degenerating fibroids cause uterine contractions (due to prostaglandin release) and fundal tenderness, a tender mass, and leukocytosis (due to inflammatory cytokine release), as seen in this patient. Diagnosis is confirmed by ultrasound, and the condition is conservatively managed with acute pain control (eg, indomethacin for patients <32 weeks gestation). (Choice A) Pregnant women are more likely to develop cholelithiasis and acute cholecystitis due to elevated estrogen levels. Patients can have right-sided abdominal pain, vomiting, and leukocytosis; however, acute cholecystitis is unlikely to cause a firm, tender mass with fundal tenderness, making this diagnosis less likely. (Choice B) Acute diverticulitis can cause abdominal pain and leukocytosis; however, patients typically have pain in the left lower, rather than the right upper, quadrant due to sigmoid colon involvement. In addition, this patient has fundal tenderness with an associated firm mass, making acute diverticulitis less likely. (Choice C) Acute pyelonephritis can cause preterm contractions and leukocytosis. In contrast to this patient with fibroid degeneration, those with pyelonephritis have flank pain, no associated abdominal mass, and an abnormal urinalysis (eg, nitrites, leukocyte esterase). (Choice E) Uterine rupture, which can occur in patients with prior cesarean delivery, can present with acute abdominal pain and a palpable mass (ie, fetal parts). However, patients typically have fetal heart rate decelerations and an acute abdomen (eg, rebound, guarding), findings not seen in this patient. fetal parts Educational objective: Leiomyomata uteri are more likely to degenerate during pregnancy because myometrial blood flow shifts toward the developing fetus and placenta. An infarcted, degenerating uterine fibroid can cause severe abdominal pain; uterine tenderness; a palpable, firm, and tender mass; and signs of inflammation (eg, leukocytosis). References: Contemporary management of fibroids in pregnancy. (http://www.ncbi.nlm.nih.gov/pubmed/20508779) Case series: pregnancy outcome in patients with uterine fibroids. (http://www.ncbi.nlm.nih.gov/pubmed/26557577)

A 33-Year-Old Woman, Gravida 2 Para 1, at 29 Weeks