Differential Diagnosis for Bright Red Bleeding and Abdominal Pain at 28 Weeks of 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 vaginal bleeding. However, at 28 weeks, the presentation might slightly differ, and abdominal pain could be associated due to other complicating factors such as placental abruption or uterine distension. The bright red bleeding is consistent with this diagnosis.

Other Likely Diagnoses

• Placental Abruption: This involves the premature separation of the placenta from the uterus, which can cause abdominal pain and vaginal bleeding. The bleeding can be bright red or concealed, leading to abdominal pain and potentially compromising fetal well-being.
• Uterine Rupture: Although less common, 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, which could be bright red.
• Preterm Labor: While not typically associated with bright red bleeding, preterm labor can cause abdominal pain and, in some cases, bleeding if there is an associated placental issue.

Do Not Miss Diagnoses

• Uterine Rupture: As mentioned, this is a critical diagnosis to consider due to its high morbidity and mortality for both mother and fetus if not promptly addressed.
• Placenta Accreta Spectrum (PAS) Disorders: These disorders involve the abnormal implantation of the placenta into the uterine wall and can lead to severe bleeding, which may be bright red, during pregnancy or postpartum. Early suspicion and management are crucial.
• Ectopic Pregnancy: Although less likely at 28 weeks, a rare possibility of an abdominal ectopic pregnancy could present with abdominal pain and bleeding. However, this would be extremely uncommon at this gestational age.

Rare Diagnoses

• Vasa Previa: This condition involves fetal blood vessels running through the membranes covering the internal cervical os, which can cause painless, bright red vaginal bleeding when these vessels rupture. It's a rare but potentially catastrophic condition for the fetus.
• Abdominal Pregnancy: An extremely rare type of ectopic pregnancy where the embryo implants in the abdominal cavity, which could potentially present with abdominal pain and bleeding at any gestational age, including 28 weeks.