4Ts

The 4Ts is a mnemonic used in obstetrics to categorize the major causes of postpartum hemorrhage, the leading cause of maternal morbidity and mortality worldwide. The four categories are Tone, Trauma, Tissue, and Thrombin. The framework supports rapid assessment and targeted management by distinguishing uterine atony, obstetric injury, retained tissue, and coagulation disorders.

Tone refers to uterine atony, the failure of the uterus to contract after delivery. It is the most common cause of postpartum hemorrhage. Risk factors include an overdistended uterus, high parity, prolonged or rapid labor, augmentation with uterotonic drugs, anesthesia, and infection. Management emphasizes uterotonic medications (with oxytocin as first line), uterine massage, and, if needed, escalation to surgical interventions.

Trauma encompasses lacerations of the cervix, vagina, and perineum, as well as uterine rupture or inversion. Bleeding from trauma may be brisk despite a soft-toned uterus. Management includes thorough examination, prompt repair, and hemostasis, with surgical intervention if necessary.

Tissue refers to retained products of conception, including placenta accreta spectrum, which prevent placental separation. Retained tissue can cause ongoing bleeding and infection. Management may involve suction or manual removal of tissue, curettage, and imaging to confirm clearance.

Thrombin denotes coagulopathy, arising from conditions such as disseminated intravascular coagulation, platelet disorders, or preexisting bleeding diatheses. It can be triggered by obstetric hemorrhage or severe preeclampsia. Management focuses on treating the underlying cause and correcting coagulopathy with tranexamic acid, appropriate blood products, and adherence to hemorrhage protocols.

The 4Ts is a practical aid for organizing assessment, but etiologies can overlap. Prompt recognition and a structured hemorrhage protocol remain essential.