The 20 most frequent principal natural categories (PNCs)
| PNC | No of adverse events in each PNC |
|---|---|
| Catheter related urinary tract infection | 37 |
| Wound infection following abdominal/retroperitoneal/pelvic procedure | 35 |
| No, delay, inadequate investigations ischaemic heart disease | 34 |
| Pressure sore/decubitus ulcer | 32 |
| Wound infection following peripheral procedure | 29 |
| Incisional hernia: post-procedural | 27 |
| Inadequate reduction of a fracture/poor alignment | 26 |
| Ongoing pain/restricted movement following back surgery | 22 |
| Pulmonary embolism postoperatively | 22 |
| GI bleed secondary to NSAID | 22 |
| Postoperative bowel obstruction/adhesions | 21 |
| Wound infection after lower segment Caesarean section | 21 |
| Recurrent incisional hernia | 20 |
| Postoperative nausea and vomiting | 20 |
| Injury due to fall in nursing home | 19 |
| Failed/blocked/ruptured/ aneurysm, vascular grafts | 17 |
| Acute pain postoperative/procedure | 16 |
| Problems following radiation therapy | 15 |
| Injury due to fall in hospital | 15 |
| Postoperative atelectasis/nosocomial pneumonia | 15 |