Differential Diagnosis for Pain in the Lower Part between the Hypogastric and Left Iliac Region in Female

Given the symptoms of pain in the lower part between the hypogastric and left iliac region in a female, even on 14 days post-ovulation (DPO) with a negative urine pregnancy test (UPT) and a resting heart rate (RHR) 4 beats per minute (bpm) more than normal for the follicular phase, the following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Ovulation Pain (Mittelschmerz): This condition is characterized by lower abdominal pain that occurs during ovulation, which typically happens around 14 DPO. The pain is usually mild and temporary but can be severe in some cases. The timing and location of the pain, along with the negative UPT, make this a plausible diagnosis.
• Other Likely Diagnoses
  • Constipation or Gastrointestinal Issues: Pain in the lower abdomen can be caused by constipation, gas, or other gastrointestinal issues. These conditions are common and can cause significant discomfort.
  • Urinary Tract Infection (UTI): Although the pain is more localized to one side, UTIs can cause lower abdominal pain, especially if the infection involves the lower urinary tract.
  • Irritable Bowel Syndrome (IBS): IBS can cause abdominal pain, bloating, and changes in bowel movements. The pain can be localized to one area of the abdomen.
• Do Not Miss Diagnoses
  • Ectopic Pregnancy: Despite the negative UPT, ectopic pregnancy must be considered, especially if there's a possibility of a very early pregnancy or a false negative test. Ectopic pregnancy is a medical emergency.
  • Appendicitis: Although the pain is not typically in the classic location for appendicitis (McBurney's point), appendicitis can present with variable pain locations, especially in females. It's a surgical emergency.
  • Ovarian Cyst or Torsion: Ovarian cysts can cause pain, and if the cyst ruptures or the ovary torsions, it becomes an emergency requiring immediate surgical intervention.
• Rare Diagnoses
  • Endometriosis: While endometriosis can cause chronic pelvic pain, it's less likely to cause acute, localized pain as described. However, it's a consideration in the differential diagnosis, especially if the pain is part of a larger pattern of symptoms.
  • Diverticulitis: This condition involves inflammation of the diverticula in the digestive tract and can cause lower abdominal pain, usually on the left side. It's more common in older adults but can occur in younger individuals.

Each of these diagnoses has a different set of implications for treatment and management, ranging from supportive care for ovulation pain or gastrointestinal issues to emergency surgical intervention for conditions like ectopic pregnancy or ovarian torsion. A thorough medical evaluation, including history, physical examination, and potentially imaging studies or laboratory tests, is necessary to determine the cause of the pain.