A Factor Level That Doesn't Predict the Bleed: Planning a Tonsillectomy Around History Instead
Her factor XI level alone would suggest a mild, low-risk deficiency — but factor XI bleeding famously doesn't track its own lab value, and her family's actual bleeding history says something the number can't.
S.B., a 16-year-old high school swimmer, is scheduled for a tonsillectomy after her fifth episode of tonsillitis this year finally convinced her ENT surgeon that watchful waiting had run its course. A routine preoperative coagulation panel turned up an isolated, prolonged activated partial thromboplastin time, and follow-up testing confirmed factor XI activity of 32 percent — a partial deficiency, inherited from her father's side of an Ashkenazi Jewish family in which the condition is well recognized, though he himself has never had a bleeding complication severe enough to be formally diagnosed until her workup prompted his own testing.
Factor XI deficiency behaves differently from hemophilia A or B in a way that matters directly to today's decision: bleeding risk correlates poorly with the factor level itself — the central observation of Seligsohn's work on the disorder — and instead tracks more closely with personal and family bleeding history and with the specific procedure being performed, since mucosal surfaces — dental extractions, tonsillectomy, urologic surgery — carry disproportionately higher bleeding risk than other surgical sites regardless of factor level, likely reflecting mucosal tissue's greater dependence on the amplification factor XI provides to thrombin generation. Her own history includes prolonged bleeding after a wisdom tooth extraction two years ago that required a return visit for repacking, and her father recalls a nosebleed after a dental cleaning that took an unusual amount of pressure to stop — a family bleeding pattern that, read together with a mucosal-surface procedure, argues for treating this as higher-risk than her 32 percent factor level would suggest on its own.
She is otherwise a healthy, competitive swimmer with no other bleeding disorders identified on her workup, and her ENT surgeon's own operative experience with her specific anatomy — large, vascular tonsils on exam — is itself an independent factor the team is weighing alongside her genetics, since two patients with an identical factor XI level can still carry meaningfully different surgical bleeding risk based on anatomy alone.
Preoperative planning, one week before the tonsillectomy
Thirty-two percent is a partial deficiency, not a severe one. If we treated every mildly reduced factor XI patient as high-risk, we'd be giving prophylactic blood products to a population where most people never have a significant bleed. I'd proceed as a standard tonsillectomy with routine perioperative care.
Factor XI is genuinely different here — bleeding risk correlates poorly with the level itself, much better with personal and family history and with procedure type. She has a documented prolonged bleed after a prior mucosal procedure, a father with a consistent though undiagnosed bleeding pattern, and tonsillectomy is itself a mucosal surgical site that carries disproportionate risk in this disorder regardless of level.
The factor level is a real data point, but treating it as the deciding one specifically for factor XI deficiency is applying a rule that holds for hemophilia A and B onto a disorder where it's known not to transfer.
I don't think this actually needs to be a disagreement once we separate the two questions being asked. Her level doesn't argue for prophylactic factor replacement — that would be overtreating a partial deficiency. But her history and the procedure type both argue for perioperative tranexamic acid, a much lower-risk intervention, with FFP held in reserve if bleeding occurs intraoperatively or postoperatively.
Agreed: perioperative tranexamic acid started the morning of surgery and continued for five days postoperatively, FFP available on standby in the OR but not administered prophylactically. Her father's own bleeding history noted in the chart as a prompt for his eventual formal testing, independent of today's decision.