Postpartum Hemorrhage and the Four Ts, Ranked by Frequency

Four causes, four words, and one of them accounts for most of what you will ever see. That is what makes this mnemonic useful rather than decorative. The published frequencies turn a list into an order of operations.

The four Ts with their published frequencies

American Family Physician, in an April 2017 review of postpartum hemorrhage prevention and treatment, ranks the four causes:

Those figures are not evenly spread. Seven in ten cases are one cause.

Tone is first because tone is most of it

A uterus that does not contract after delivery cannot clamp the vessels where the placenta was attached. Bleeding follows from that mechanical failure, and it can be brisk.

This is why the fundus is assessed first and assessed often. A boggy uterus is the physical finding that matches the commonest cause, and finding it early is the difference between a fundal massage and a resuscitation.

So in an item that describes heavy bleeding after delivery, the first assessment is almost never a laboratory value. Palpate the fundus. The answer is usually in your hand before it is in the chart.

Trauma, tissue and thrombin

Trauma sits second at roughly 20%. A firm, well contracted uterus with continued bleeding points here, because the uterus is doing its job and blood is coming from somewhere else. Lacerations of the cervix, vagina or perineum are the usual sources.

Tissue sits third at roughly 10%. Retained placental fragments keep the uterus from contracting down completely, and the history usually includes something about the placenta not being delivered intact.

Thrombin sits last at roughly 1%. A coagulation problem is rare, and it tends to arrive with a story attached rather than out of nowhere. Bleeding from puncture sites and oozing that will not stop are the descriptions to watch for.

What each T looks like at the bedside

The names stay abstract until you attach a finding to each one, so attach them now.

Tone shows up as a uterus that feels soft or boggy on palpation, often sitting higher than expected and displaced to one side if the bladder is full.

Trauma shows up as steady bleeding from a uterus that feels firm, and as visible injury on inspection of the cervix, vagina or perineum.

Tissue shows up as continued bleeding with a uterus that will not stay contracted, usually alongside a note that the placenta was delivered incomplete.

Thrombin shows up as bleeding from places nobody injured. Oozing from an intravenous site. A puncture that keeps refilling.

Four causes, four findings. That pairing turns a mnemonic into an assessment.

The definition and its time window

Early postpartum hemorrhage, as that review states ACOG's definition, is a total blood loss of at least 1,000 mL, or blood loss accompanied by signs or symptoms of hypovolemia, within 24 hours of delivery.

Read the middle clause again. The definition does not require a measured volume at all.

Why the second clause matters more than the number

Blood loss is notoriously hard to estimate by eye, and a patient can be in trouble before anybody has measured anything. So the definition builds in a second route: signs or symptoms of hypovolemia, whatever the measured volume says.

That is the clause item writers use. A stem gives you a patient with a rising heart rate, falling blood pressure, pallor and light headedness after delivery, and no volume figure anywhere in the case. The definition is met.

A firm number is comforting. Do not wait for one.

Why the ranking is a bedside tool

When bleeding starts, you do not have time to work through four possibilities equally. The frequencies give you an order, and the order gives you a first action.

Check tone. If the uterus is boggy, you are most likely in the 70% and the intervention follows. If the uterus is firm, that finding has just moved you down the list toward trauma, and inspection is what comes next.

That is reasoning, not recall. The mnemonic holds the names, and the frequencies hold the sequence.

Risk factors do not reorder the list. A patient with a known clotting disorder still gets her fundus checked first, because a boggy uterus remains the likeliest cause of the bleeding in front of you. History raises suspicion. It does not replace assessment.

A worked stem

A patient delivered forty minutes ago and her pad is saturating faster than expected. Her heart rate has climbed and her pressure has drifted down. No volume has been measured.

The definition is already met through its second clause, because signs of hypovolemia are present regardless of what any measurement would have said.

Now assess in the order the frequencies give you. Palpate the fundus. If it is boggy, you are in the commonest cause and the intervention follows from that finding.

If it is firm, the assessment has just done its job. Firm tone with continued bleeding moves you toward trauma, and inspection is the next step rather than more massage.

Before delivery, a different pattern was being read

Much of the obstetric content around this one is about the period before the birth, where the monitor rather than the fundus is the thing being interpreted. The three tier system for describing a tracing is explained in fetal heart rate categories one, two and three, and the mechanisms behind the different deceleration shapes are in early, late and variable decelerations, sorted by mechanism.

Hypertensive complications are a separate chain of criteria with their own thresholds, and they start with the baseline definition in preeclampsia diagnostic criteria in plain numbers.

Scope differs by track

PN candidates meet this content too, usually from the observation and reporting side rather than the interpretation side. What that looks like in practice is set out in newborn and maternity content a PN candidate actually needs.

For either track, the takeaway is the same shape. Four causes, one that dominates, and a definition with two doors into it. Where these items sit in the wider exam is mapped in maternity and newborn questions and what is really being tested.