Differential Diagnosis for Bright Red Bleeding and Abdominal Pain in Pregnancy

Single Most Likely Diagnosis

• Placenta Previa: This condition is characterized by the placenta partially or completely covering the internal cervical os, leading to painless, bright red vaginal bleeding in the second or third trimester. The abdominal pain mentioned could be secondary to associated uterine contractions or other complications.

Other Likely Diagnoses

• Placental Abruption: Also known as placental abruption, this condition involves the premature separation of the placenta from the uterus. It typically presents with painful vaginal bleeding and can cause abdominal pain due to the uterine contractions and irritation of the peritoneum.
• Uterine Rupture: Although more rare, uterine rupture can occur, especially in women with a history of uterine surgery (like a previous cesarean section). It presents with severe abdominal pain and potentially vaginal bleeding, including bright red blood.
• Ovarian Torsion: This is a condition where the ovary twists around its ligaments, cutting off its blood supply. It can cause severe abdominal pain and might be associated with vaginal bleeding, though this is less common.

Do Not Miss Diagnoses

• Ectopic Pregnancy: Although ectopic pregnancy typically presents early in pregnancy, it's crucial not to miss this diagnosis due to its high mortality rate if ruptured. Symptoms include abdominal pain and vaginal bleeding, which can be bright red.
• Ruptured Ovarian Cyst: While often not life-threatening, a ruptured ovarian cyst can mimic more severe conditions and cause significant pain and bleeding.

Rare Diagnoses

• Vasa Previa: A condition where fetal blood vessels are exposed in the lower uterine segment, unsupported by the umbilical cord or placental tissue. Rupture of these vessels can lead to fetal exsanguination and maternal bleeding.
• Uterine Artery Aneurysm Rupture: An extremely rare condition that could present with abdominal pain and bleeding, though it's more commonly associated with other symptoms.

Each of these diagnoses requires prompt evaluation and management to ensure the best outcomes for both mother and fetus. The approach to diagnosis involves a combination of clinical assessment, ultrasound imaging, and sometimes additional diagnostic tests to determine the cause of the symptoms accurately.