Also known as: Kidney failure
Katie is one of conjoined twins who requires a kidney transplant from her identical twin sister Jenny. This drives the major surgical storyline of the episode.
Also known as: Conjoined twins joined at the head
The twin sisters are connected at the skull and share a single brain mass with a shared sagittal sinus vein. The separation surgery is a central focus of the episode, complicated by the need to perform it earlier than planned due to Jenny's heart failure.
Also known as: CHF
Jenny develops end-stage heart failure following post-operative complications from the kidney donation. This necessitates moving up the separation surgery from six months to one day post-transplant to reduce strain on her failing heart.
Jenny experiences a post-operative renal vein rupture after donating her kidney to Katie, causing internal bleeding and requiring emergency re-opening of the surgical site. This complication triggers her heart failure.