ConditionWhole body & general
Surgical Complications
Surgical complications are problems that develop during or after an operation. Most surgery goes smoothly, but complications can include wound infection, bleeding, blood clots in the legs or lungs, pneumonia, urinary problems, a reopened wound, reactions to anesthesia and delirium. Many appear days after you go home, so knowing the warning signs matters. Fever, a red or draining wound, calf swelling, chest pain or breathlessness, and severe or worsening pain after surgery all need prompt medical attention.
Also called: Postoperative complications, complications of surgery, post-surgical complications
At a glance
- What they are
- Unplanned problems during or after an operation.
- Most common
- Wound infection, bleeding, blood clots, pneumonia, urinary retention, ileus, nausea, delirium.
- Timing
- Some occur in hospital; many appear 3 to 14 days after surgery.
- Risk factors
- Older age, smoking, obesity, diabetes, heart or lung disease, emergency or long surgery.
- Prevention
- Early walking, breathing exercises, blood clot prevention, wound care, stopping smoking.
When to get help
Call 911 or go to the ER
- Chest pain, sudden shortness of breath or coughing blood (possible pulmonary embolism)
- Heavy bleeding through dressings, or vomiting blood
- Confusion, fainting, a racing heart, or cold, clammy skin (possible sepsis or bleeding)
- A wound that has burst open with tissue or organs visible
- Severe belly pain with a hard, swollen belly after abdominal surgery
See a doctor within a day or two
- Fever over 38 °C (100.4 °F) or chills
- A wound that is increasingly red, hot, swollen, painful, or draining pus or cloudy fluid
- Calf pain, warmth or swelling in one leg
- Not passing urine for 8 hours or more, or a painful, full bladder
- Persistent vomiting, not passing gas or stool for several days, or a swollen belly
- Pain getting worse rather than better, or not controlled by prescribed medicine
Book a routine appointment
- Mild redness at the wound edges that is not spreading
- Constipation from pain medicine
- Low mood, poor sleep or memory problems in the weeks after surgery
Usually safe to manage at home
- Expected mild pain, bruising and tiredness that steadily improve each day
Common complications after surgery
| Complication | Timing | Warning signs |
|---|---|---|
| Surgical site infection | 3 to 30 days | Redness, warmth, swelling, pus, fever |
| Wound dehiscence | 5 to 10 days | Wound edges separate, sudden pink fluid leakage |
| Bleeding or hematoma | Hours to days | Swelling, bruising, blood soaking dressings, dizziness |
| Deep vein thrombosis | Days to weeks | Calf pain, swelling, warmth in one leg |
| Pulmonary embolism | Days to weeks | Sudden breathlessness, chest pain, fast heart rate |
| Pneumonia and atelectasis | 1 to 5 days | Fever, cough, breathlessness |
| Ileus | 1 to 5 days | Bloating, vomiting, no gas or stool |
| Urinary retention or infection | Hours to days | Unable to pass urine, burning, frequency |
| Delirium | 1 to 3 days | Sudden confusion, agitation or drowsiness, especially in older adults |
| Postoperative nausea and vomiting | Hours | Nausea, vomiting after anesthesia |
| Anastomotic leak (bowel surgery) | 3 to 10 days | Fever, worsening belly pain, fast heart rate |
Anesthesia-related complications
- sore throat from the breathing tube
- nausea and vomiting
- dental injury
- allergic reactions
- rarely, malignant hyperthermia, a dangerous reaction to certain anesthetic gases
- post-dural puncture headache after spinal or epidural anesthesia
- postoperative cognitive dysfunction in older adults
Who is at higher risk
- older age and frailty
- smoking
- obesity
- diabetes, especially with high blood sugar around surgery
- heart, lung, kidney or liver disease
- weakened immune system or steroid use
- poor nutrition
- emergency, long or complex operations
- previous blood clots
How complications are prevented
Before surgery
- stop smoking, ideally 4 to 8 weeks before
- control blood sugar and blood pressure
- improve nutrition and fitness ("prehabilitation") where possible
- review medicines, especially blood thinners, diabetes medicines and supplements
- bathe as instructed with antiseptic soap
In hospital
- antibiotics given just before surgery for many operations
- blood clot prevention: compression devices, stockings, injections or tablets
- early walking, often the same or next day
- breathing and coughing exercises, incentive spirometry
- good pain control so you can move and breathe deeply
- early eating and drinking when safe
- removing urinary catheters and IV lines as soon as possible
At home
- keep the wound clean and dry as instructed and wash hands before touching it
- walk several times a day
- take blood clot prevention medicine if prescribed
- avoid heavy lifting as advised (often 6 weeks for abdominal surgery)
- take pain medicine as directed, with stool softeners if using opioids
- know who to call with concerns
Frequently asked questions
What are the most common complications after surgery?
The most common are wound infection, bleeding, blood clots in the legs or lungs, pneumonia, urinary problems, nausea and vomiting, slow bowel recovery (ileus) and delirium in older adults. Most are preventable or treatable when found early.
What are signs of infection after surgery?
Watch for increasing redness, warmth, swelling or pain around the wound, pus or cloudy drainage, a bad smell, and fever over 38 °C (100.4 °F) or chills. Contact your surgical team promptly if these occur.
How do I know if I have a blood clot after surgery?
A clot in the leg causes pain, swelling, warmth or redness, usually in one calf. A clot in the lungs causes sudden breathlessness, chest pain that is worse on breathing, a fast heart rate or coughing blood, which is an emergency.
When should I call my doctor after surgery?
Call for fever, a worsening wound, calf swelling, inability to urinate, persistent vomiting, or pain that is getting worse instead of better. Call 911 or your local emergency number for chest pain, breathing difficulty, heavy bleeding or confusion.
Sources
This guide was written from current patient and clinical guidance, including:
- American College of Surgeons: Patient education, what to expect after surgery
- CDC: Surgical site infection (SSI)
- Agency for Healthcare Research and Quality: Preventing hospital-acquired venous thromboembolism
- MedlinePlus: After surgery
- American Society of Anesthesiologists: Anesthesia risks and recovery