Differential Diagnosis for Laura's Presentation

• Single Most Likely Diagnosis
  • Pelvic Inflammatory Disease (PID): This is the most likely diagnosis given Laura's history of untreated sexually transmitted infections (chlamydia and gonorrhea), symptoms of daily nausea, vomiting, dysuria, cloudy yellow mucoid cervical discharge, friable cervix, cervical motion tenderness (CMT), and the presence of leukocytes, nitrates, and ketones in her urine. The fact that she is sexually active without proper contraception and has a history of STIs increases her risk for PID.
• Other Likely Diagnoses
  • Ectopic Pregnancy: Although the urine pregnancy test is positive and an 8-week size uterus is palpable, ectopic pregnancy should be considered, especially given Laura's history of PID risk factors, which also increase the risk for ectopic pregnancy.
  • Urinary Tract Infection (UTI): The presence of dysuria, nitrates, and leukocytes in the urine suggests a UTI, which could be a concurrent infection or a separate diagnosis.
  • Vaginitis: The cloudy, yellow mucoid cervical discharge could also suggest vaginitis, potentially due to bacterial vaginosis or trichomoniasis, especially in the context of her sexual activity and previous STIs.
• Do Not Miss Diagnoses
  • Septic Abortion: Although less likely given the positive pregnancy test and the absence of reported abortion attempts, septic abortion is a potentially life-threatening condition that must be considered, especially if Laura's boyfriend's withdrawal method failed and she attempted to terminate the pregnancy.
  • Ruptured Ectopic Pregnancy: This is a medical emergency that could present with severe abdominal pain, vomiting, and potentially life-threatening hemorrhage. It's crucial to rule out ectopic pregnancy, especially with Laura's risk factors.
  • Appendicitis: While less likely given the specific gynecological symptoms, appendicitis can present with nausea, vomiting, and abdominal pain and must be considered in the differential diagnosis of abdominal pain in a pregnant patient.
• Rare Diagnoses
  • Cervical Cancer: Although extremely rare in a 16-year-old, any abnormal cervical findings, especially with a history of high-risk sexual behavior, warrant consideration of cervical cancer or its precursors.
  • Tuberculous Salpingitis: In areas where tuberculosis is prevalent, tuberculous salpingitis could be a rare cause of PID symptoms, especially if Laura has been exposed to tuberculosis. However, this would be less likely in the context provided.