Kaplan USMLE Step 3: 36-hour history of lower abdominal pain

If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 3 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.

A 17-year-old female patient is brought to the emergency department by her mother because of a 36-hour history of lower abdominal pain. The girl has been a compliant patient of yours for 10 years, and at her last routine visit she told you that she is sexually active with three different partners and uses condoms for contraception "most of the time." Her last menstrual period was 4 days ago. Her temperature is 38.8ºC (101.8ºF), blood pressure is 110/70 mm Hg, and pulse is 65/min.

Physical examination shows bilateral lower abdominal tenderness, but rebound tenderness and guarding are absent. Pelvic examination shows cervical motion tenderness and adnexal tenderness, and a moderate amount of yellowish-white discharge is present on the cervical os. There are no palpable masses. A urine pregnancy test is negative. Cervical cultures are taken and sent to pathology for evaluation. Laboratory studies show:

• Erythrocyte sedimentation rate: 45/mm³
• Hemoglobin: 13 g/dL
• Hematocrit: 38%
• Leukocyte count: 13,000/mm³

Which of the following is the most appropriate next step in management of this patient?

A. Admit her to the hospital and begin cefoxitin and doxycycline therapy, intravenously

B. Admit her to the hospital and prepare her for an immediate operation

C. Do culdocentesis

D. Contact her male sexual partners for evaluation and treatment

E. Start patient on IM ceftriaxone and oral azithromycin therapy and send her home

The correct answer is E.

The diagnosis of pelvic inflammatory disease (PID) is based on clinical findings such as lower abdominal tenderness, cervical motion tenderness, adnexal tenderness, a vaginal or cervical discharge, fever >38.3ºC, (101.0ºF), elevated erythrocyte sedimentation rate and C-reactive protein, and laboratory documentation of Neisseria gonorrhoeae or Chlamydia trachomatis. Treatment should be given even before the culture results return, to reduce the risks of infertility and progressive infection. Since this girl is a compliant patient, it is appropriate to start the patient on IM ceftriaxone and oral azithromycin therapy and send her home. Admission used to be recommended for all adolescents with PID, but this is no longer the case.

However, the Centers for Disease Control recommends admission for the following individuals, including:

• Noncompliant patients in whom follow-up cannot be assured
• Pregnant patients with PID
• Patients with severe nausea and vomiting precluding outpatient management
• Patients with an abscess or peritonitis
• Immunodeficient patients with PID
• All those who fail outpatient therapy

Choice A. It is not necessary to admit this girl to the hospital and begin IV cefoxitin and doxycycline therapy because outpatient treatment is sufficient in a compliant patient.